/*
 *  The Mana Client
 *  Copyright (C) 2009-2012  The Mana Developers
 *
 *  This file is part of The Mana Client.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "net/download.h"

#include "configuration.h"
#include "log.h"
#include "main.h"

#include "utils/stringutils.h"

#include <SDL.h>
#include <SDL_thread.h>

#include <zlib.h>

const char *DOWNLOAD_ERROR_MESSAGE_THREAD = "Could not create download thread!";

namespace Net {

/**
 * Calculates the Alder-32 checksum for the given file.
 */
unsigned long Download::fadler32(FILE *file)
{
    if (!file || fseek(file, 0, SEEK_END) != 0)
        return 0;

    const long fileSize = ftell(file);
    if (fileSize < 0)
        return 0;

    rewind(file);

    // Calculate Adler-32 checksum
    void *buffer = malloc(fileSize);
    const size_t read = fread(buffer, 1, fileSize, file);
    unsigned long adler = adler32_z(0L, Z_NULL, 0);
    adler = adler32_z(adler, (Bytef*) buffer, read);
    free(buffer);

    return adler;
}


Download::Download(void *ptr, const std::string &url,
                   DownloadUpdate updateFunction):
        mPtr(ptr),
        mUrl(url),
        mUpdateFunction(updateFunction)
{
    mError = (char*) malloc(CURL_ERROR_SIZE);
    mError[0] = 0;

    mOptions.cancel = false;
}

Download::~Download()
{
    if (mHeaders)
        curl_slist_free_all(mHeaders);

    int status;
    SDL_WaitThread(mThread, &status);
    free(mError);
}

void Download::addHeader(const std::string &header)
{
    mHeaders = curl_slist_append(mHeaders, header.c_str());
}

void Download::noCache()
{
    addHeader("pragma: no-cache");
    addHeader("Cache-Control: no-cache");
}

void Download::setFile(const std::string &filename,
                       std::optional<unsigned long> adler32)
{
    mOptions.memoryWrite = false;
    mFileName = filename;
    mAdler = adler32;
}

void Download::setWriteFunction(WriteFunction write)
{
    mOptions.memoryWrite = true;
    mWriteFunction = write;
}

bool Download::start()
{
    logger->log("Starting download: %s", mUrl.c_str());

    mThread = SDL_CreateThread(downloadThread, "Download", this);

    if (!mThread)
    {
        logger->log("%s", DOWNLOAD_ERROR_MESSAGE_THREAD);
        strcpy(mError, DOWNLOAD_ERROR_MESSAGE_THREAD);
        mUpdateFunction(mPtr, DOWNLOAD_STATUS_THREAD_ERROR, 0, 0);

        return false;
    }

    return true;
}

void Download::cancel()
{
    logger->log("Canceling download: %s", mUrl.c_str());

    mOptions.cancel = true;
    if (mThread && SDL_GetThreadID(mThread) != 0)
    {
        SDL_WaitThread(mThread, nullptr);
        mThread = nullptr;
    }
}

const char *Download::getError() const
{
    return mError;
}

int Download::downloadProgress(void *clientp,
                               curl_off_t dltotal, curl_off_t dlnow,
                               curl_off_t ultotal, curl_off_t ulnow)
{
    auto *d = reinterpret_cast<Download*>(clientp);

    if (d->mOptions.cancel)
    {
        return d->mUpdateFunction(d->mPtr, DOWNLOAD_STATUS_CANCELLED,
                                  (size_t) dltotal, (size_t) dlnow);
        return -5;
    }

    return d->mUpdateFunction(d->mPtr, DOWNLOAD_STATUS_IDLE,
                              (size_t) dltotal, (size_t) dlnow);
}

int Download::downloadThread(void *ptr)
{
    int attempts = 0;
    bool complete = false;
    auto *d = reinterpret_cast<Download*>(ptr);
    CURLcode res;
    std::string outFilename;

    if (!d)
    {
        return 0;
    }
    if (!d->mOptions.memoryWrite)
    {
        outFilename = d->mFileName + ".part";
    }

    while (attempts < 3 && !complete && !d->mOptions.cancel)
    {
        FILE *file = nullptr;

        d->mUpdateFunction(d->mPtr, DOWNLOAD_STATUS_STARTING, 0, 0);

        if (d->mOptions.cancel)
        {
            d->mThread = nullptr;
            return 0;
        }

        d->mCurl = curl_easy_init();

        if (d->mCurl && !d->mOptions.cancel)
        {
            logger->log("Downloading: %s", d->mUrl.c_str());

            curl_easy_setopt(d->mCurl, CURLOPT_FOLLOWLOCATION, 1);
            curl_easy_setopt(d->mCurl, CURLOPT_HTTPHEADER, d->mHeaders);

            if (d->mOptions.memoryWrite)
            {
                curl_easy_setopt(d->mCurl, CURLOPT_FAILONERROR, 1);
                curl_easy_setopt(d->mCurl, CURLOPT_WRITEFUNCTION, d->mWriteFunction);
                curl_easy_setopt(d->mCurl, CURLOPT_WRITEDATA, d->mPtr);
            }
            else
            {
                file = fopen(outFilename.c_str(), "w+b");
                curl_easy_setopt(d->mCurl, CURLOPT_WRITEDATA, file);
            }

            const std::string appShort = branding.getStringValue("appShort");
            const std::string userAgent =
                    strprintf(PACKAGE_EXTENDED_VERSION, appShort.c_str());

            curl_easy_setopt(d->mCurl, CURLOPT_USERAGENT, userAgent.c_str());
            curl_easy_setopt(d->mCurl, CURLOPT_ERRORBUFFER, d->mError);
            curl_easy_setopt(d->mCurl, CURLOPT_URL, d->mUrl.c_str());
            curl_easy_setopt(d->mCurl, CURLOPT_NOPROGRESS, 0);
            curl_easy_setopt(d->mCurl, CURLOPT_XFERINFOFUNCTION, downloadProgress);
            curl_easy_setopt(d->mCurl, CURLOPT_XFERINFODATA, ptr);
            curl_easy_setopt(d->mCurl, CURLOPT_NOSIGNAL, 1);
            curl_easy_setopt(d->mCurl, CURLOPT_CONNECTTIMEOUT, 15);

            if ((res = curl_easy_perform(d->mCurl)) != 0 && !d->mOptions.cancel)
            {
                switch (res)
                {
                case CURLE_ABORTED_BY_CALLBACK:
                    d->mOptions.cancel = true;
                    break;
                case CURLE_COULDNT_CONNECT:
                default:
                    logger->log("curl error %d: %s host: %s",
                                res, d->mError, d->mUrl.c_str());
                    break;
                }

                if (d->mOptions.cancel)
                {
                    break;
                }

                d->mUpdateFunction(d->mPtr, DOWNLOAD_STATUS_ERROR, 0, 0);

                if (!d->mOptions.memoryWrite)
                {
                    fclose(file);
                    ::remove(outFilename.c_str());
                }
                attempts++;
                continue;
            }

            curl_easy_cleanup(d->mCurl);

            if (!d->mOptions.memoryWrite)
            {
                // Don't check resources.xml checksum
                if (d->mAdler)
                {
                    unsigned long adler = fadler32(file);

                    if (d->mAdler != adler)
                    {
                        fclose(file);

                        // Remove the corrupted file
                        ::remove(d->mFileName.c_str());
                        logger->log("Checksum for file %s failed: (%lx/%lx)",
                            d->mFileName.c_str(),
                            adler, *d->mAdler);
                        attempts++;
                        continue; // Bail out here to avoid the renaming
                    }
                }
                fclose(file);

                // Any existing file with this name is deleted first, otherwise
                // the rename will fail on Windows.
                ::remove(d->mFileName.c_str());
                ::rename(outFilename.c_str(), d->mFileName.c_str());

                // Check if we can open it and no errors were encountered
                // during renaming
                file = fopen(d->mFileName.c_str(), "rb");
                if (file)
                {
                    fclose(file);
                    complete = true;
                }
            }
            else
            {
                // It's stored in memory, we're done
                complete = true;
            }
        }
        if (d->mOptions.cancel)
        {
            d->mThread = nullptr;
            return 0;
        }
        attempts++;
    }

    if (d->mOptions.cancel)
    {
        // Nothing to do...
    }
    else if (!complete || attempts >= 3)
    {
        d->mUpdateFunction(d->mPtr, DOWNLOAD_STATUS_ERROR, 0, 0);
    }
    else
    {
        d->mUpdateFunction(d->mPtr, DOWNLOAD_STATUS_COMPLETE, 0, 0);
    }

    d->mThread = nullptr;
    return 0;
}

} // namespace Net